Six years ago, just 3% of the insulation installed in new homes in the United States was spray foam, but by 2012 spray foam’s market share was nearly four times as big. Last year, according to a survey from the Home Innovation Research Labs, its market share fell to about 8%, as more builders returned to an old favorite: fiberglass.

The Home Innovation Annual Builder Practices Survey found that fiberglass batts and blown-in fiberglass continue to dominate the insulation market, with shares of 55% and 19%, respectively. Other choices include rockwool, rigid foam, and cellulose.

“While we all recognize that a one-year data shift does not constitute a trend in building-product usage, this may be signaling a change in the home-insulation landscape,” the report said.

Researchers found a variety of reasons for the earlier spike in interest for spray-foam insulation, a more expensive option than cellulose or fiberglass but one that is appreciated for its high R-values (roughly R-6 per in. for closed-cell spray polyurethane) and its air-sealing qualities in floors, walls, and roofs.

Using closed-cell foam on the underside of the roof deck turns an attic into a conditioned space and allows builders to put heating and air-conditioning ducts as well as HVAC equipment in the attic without paying an energy penalty. Builders had an easier time of explaining the benefits of spray foam to homebuyers, the report said, and using the insulation made it easier for them to comply with tougher energy codes.

Some builders are still willing to pay the higher cost for spray-foam insulation, and it has found a niche in luxury homes and with builders who do 10 or fewer homes per year, the report said. But overall, fiberglass is king, making up about 75% of the new-home market. 

Why the overall decline?

The report said it’s not entirely clear why fewer builders seem to be using spray foam, but it acknowledged the Annual Builder Practices Survey of 2013, which found that builders were trying to economize by using fewer and less expensive materials in the houses they build.

In addition, there are now other options for building well-insulated, airtight homes, including the Zip roof and wall systems developed by Huber, spray-on air sealants, denser fiberglass batts with higher R-values per inch, raised-heel trusses (also called energy trusses) that allow more insulation to be installed at the perimeter of the building, and foam-board wall sheathing.

Another possible explanation comes in the mix of homes that are being built. Spray-foam insulation is more common in high-end homes, the report said, but the market seems to be shifting toward multifamily rentals.

“And there is another very simple reason that may be at play-some home builders tried spray foam insulation but have returned to the materials they were using before,” the report says. “A survey conducted by Home Innovation Labs in 2013 showed that 30 percent of builders who have used spray foam in the past are not using it now.

“In our research, we often hear builders state that fiberglass, by far the most popular home insulation material, is simply the most cost-effective, easy-to-install material for most applications.” 

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